1. Technical Field
The present invention relates to an activated EU-2 zeolite and use thereof. More particularly, the present invention relates to an EU-2 zeolite, the activity thereof for a hydroisomerization reaction (particularly, a reaction for converting n-paraffin into iso-paraffin) is improved by increasing pores with specific sizes while maintaining the crystal structure thereof, a method of preparing the same, and a method of hydroisomerizing or hydrodewaxing various hydrocarbon fractions using the EU-2 zeolite.
2. Description of the Related Art
In an oil refining process for producing lube oil, diesel oil and the like, a hydroisomerization reaction for converting n-paraffin into iso-paraffin becomes more important. The reason for this is that n-paraffin does not meet the recently required standards of fuel oil and lube oil products because long-chain n-paraffins show the poor cold flow properties. Particularly, recently, the quality of raw materials has been deteriorated by the influence of rise of oil price, but on the other hand, high-quality fuel oil and lube oil products have been required with the advancement of automobile engine technologies. For example, the hydroisomerization reaction can be put to practical use in a process of producing gasoline with a high octane number gasoline using hydrocarbons of C4-C7, a process of producing high-quality diesels with high cetane number having improved cold flow properties using hydrocarbons of C7-C15 and a process of producing high-grade lube oil having a high viscosity index using n-paraffin of C15 or more.
This hydroisomerization reaction is known to be generally performed by a bi-functional catalyst. Here, the bi-functional catalyst is composed of a metal composition having functions for hydrogenation/dehydrogenation and a support having acid sites for skeletal isomerization. In relation to this, various materials, such as silica-alumina, clay and zeolite, are known as a support having acid sites. Particularly, among these materials, zeolite is suitable for a hydroisomerization reaction because it has a stable structure even under severe reaction conditions and has a large surface area and a large number of acid sites.
It was reported that researches into zeolite materials having excellent shape selectivity for maximizing a hydroisomerization reaction and inhibiting the cracking of hydrocarbons (feedstocks) have been made, and, among these zeolite materials, zeolite materials (ZSM-22, ZSM-23, EU-2, ZSM-48 and the like) having a uni-dimensional 10-ring pore structure had excellent selectivity to a hydroisomerization reaction.
According to the catalog of International Zeolite Association (IZA), EU-2 belongs to the ZSM-48 family together with ZSM-48, ZBM-30 and EU-11. These zeolites have similar XRD patterns, that is, crystal structures.
As described above, U.S. Pat. No. 6,984,309 discloses a technology for improving paraffin properties (particularly, viscosity index, pour point, etc.) of hydrocarbon fractions by performing a hydroisomerization reaction in the presence of a catalyst including EU-2 (or EU-2 and a binder) as a support and supported with a hydrogenated metal. However, this technology corresponds to a technology for changing the distribution characteristics of supported precious metal particles rather than changing the properties of EU-2 itself.
Meanwhile, technologies for improving hydroisomerization performance by reforming the properties of EU-2 itself are also known.
As typical examples of such technologies, U.S. Pat. Nos. 6,923,949 and 7,482,300 disclose a zeolite synthesis method for improving the purity of a crystal structure of ZSM-48 belonging to the same family as EU-2 under the usage of specific seeds or under the absence of seeds. Further, it is disclosed in the Patent documents that the zeolite ZSM-48 manufactured by this method can exhibit improved hydroisomerization effects.
Meanwhile, as a technology for improving catalytic performance by reforming the previously-synthesized EU-2 zeolite by particular post-treatment, WO2012/055755 A1 discloses a catalyst, the hydroconversion activity (particularly, dewaxing activity) of which is improved by bringing EU-2 zeolite into contact with a solution containing an organic acid of 2 to 6 carbon atoms, particularly, a fluorine-containing salt. In this case, most of the above-mentioned conventional technologies are based on EU-2 zeolite having pores of 30 to 40 Å.
However, in order to meet the requirements for hydroisomerization or hydrodewaxing activity, it is additionally required to improve the properties of EU-2 itself.